by Jeff Gluck, USA TODAY Sports

by Jeff Gluck, USA TODAY Sports

AVONDALE, Ariz. - Dale Earnhardt Jr.'s hands shook as he squeezed a water bottle, forcing as much cool liquid into his mouth as he could.

A hard-fought fifth-place finish Sunday at Phoenix International Raceway left him looking physically drained, and it was all he could do to maintain his track position on a day when passing was at a premium.

Earnhardt had "a good enough car to win the race," he said, but lost the lead to eventual winner Carl Edwards when Casey Mears pulled down in front of him on pit road.

"I had to stop almost, and that was it," he said of the lap 239 pit stop. "That was my opportunity to win."

But what left Earnhardt feeling exhausted was the effort it took to get a top-five result with NASCAR's new Gen 6 car. Despite hopes the new car would immediately make it easier for drivers to pass, Earnhardt said that wasn't the case.

Drivers have long struggled with what they refer to as "dirty air," similar to the turbulent pocket of air felt by a driver who gets stuck behind a semi truck on the freeway. While racing at high speeds, the dirty air forms a bubble that makes it difficult for drivers to pass each other.

"If there's something in front of you the size of a car, it's going to be hard to get clean air on the front end," Earnhardt said. "I don't care what they do with the package, it's not going to get much better."

"It's got tons of great potential," he added. "(The previous model) was a hunk of junk when we first started out with it. From how far we brought that thing in three years, this thing is going to be pretty awesome."

He was disappointed not to win, but he's been a non-factor at Phoenix. Earnhardt came in with one top-10 finish in his last eight starts.

"I'm hoping this is a sign we're a much better race team than last year," he said. "We definitely improved here."